Continuous linear lighting are used to highlight architectural elements while providing primary and accent lighting. Such fixtures are often used to illuminate coves, pathways, walkways, shelving, countertops, etc. Linear lighting systems previously employed incandescent and festoon type light bulbs selectively arranged within a mounting track. One of ordinary skill in the art will appreciate the bulbs associated with traditional systems present many drawbacks such as 1) excessive heat, 2) high lamp replacement cost, 3) regular service labor costs, 4) increased size, and/or 5) minimal features and options. In an attempt to address these issues, designers and architects initially turned to “rope lights” comprised of interconnected LED lighting elements.
Although rope lights have a lifespan greater than their predecessors, they still have drawbacks—dimming difficulties, lack of color rendering consistency, and poor light diffusion. Although the market has increasingly demanded improved performance from the latest LED-related technology to adequately replace the old incandescent and fluorescent lights, rope lights have not become a professional standard for linear lighting applications.
Lighting manufacturers have sought to address the drawbacks associated with the prior art by providing “tape lights” (also referred to herein as “LED tape”), that are similar to rope lights but employ brighter and more efficient LED lighting elements and other associated components and drivers. Tape lights are usually comprised of a substrate having a first surface that accommodates one or more LED lighting elements and a second surface at least partially comprised of an adhesive. Conductors used to interconnect adjacent LED lighting elements are integrated within the substrate thickness. Tape lights were welcomed by the industry because they present a compact form-factor and high-output lighting. Unfortunately, as those of ordinary skill in the art will appreciate, architects and builders sometimes avoid tape lights as light “tape” is often not viewed as a proper light “fixture.” LED tape is also sometimes avoided because it is difficult and time consuming to interconnect lengths of tape to create an elongate tape element.
Tape lights are desirable as the length of a tape light strip can be selectively decreased by cutting the substrate between LED lighting elements. Some tape light systems employ cut points along their length that are marked with a cutline indicator because severing the tape light in locations other than predefined cut points would adversely affect the functionality of the system. The cut points often are associated with positive and negative contact terminals that later accept connectors used to fix the severed end to a power supply or to another tape segment. Hand soldering, a meticulous and time-consuming process, is normally the preferred method to interconnect the cut end of a light tape strip to a power source, for example.
Alternatively, a mechanical connector may be used that employs positive and negative conductors. Mechanical connectors rely on pressure to maintain contact between the positive and negative conductors with corresponding contact terminals at the severed end of the tape and often fail because the connected components (i.e., leads/conductors) are very small. Further, users often cut the LED tape strip incorrectly and, thus, do not provide sufficient conductor surface area at the contact terminal to receive and secure the mechanical connector. If the tape light is cut, for example, a millimeter to the left or right of the cutline, the small contact terminals would either be misaligned or engage the incorrect terminal of the mechanical connector, which could cause melting, fire, or create a shock hazard. Further, the mechanical connection provided by pressure connectors is tenuous, and easily broken with a slight tug. The prior art method of connecting tape lights severed at a cut line is shown and described in U.S. Pat. No. 8,262,250 to Li et al, which is incorporated by reference herein.
That is, the lights used in LED tape are also often important. That is, many have attempted to create lighting devices capable of emulating white light or sunlight. These attempts sometimes result in using LEDs that may have many advantages over incandescent light sources including lower energy consumption, less heat, longer lifetime, improved physical robustness, smaller size, and faster switching. However, it may be very expensive and difficult to emulate white light or sun light with LEDs. More specifically, LED lighting may produce “pixalized” light, where individual LED lights produce non-uniform light such that one can tell there are individual light sources instead of a continuous source. To address this issue in linear LED lighting fixtures, a lens or optic needs to be moved toward the LEDs and the space between each LED (“pitch”) needs to be minimized. Without doing so, unsightly pixilation can occur, which is unacceptable for direct-view installations.
Pixel pitch increases exponentially with the introduction of colored LEDs as the space between each color becomes the visible pitch that requires mitigation. The simplest way to create a diffused, warm-dimming type, architectural, dynamic lighting fixture is to utilize the fewest number of LED's per increment. The ultimate goal is to represent the visible light spectrum with specific and repeatable spectral values or useful warm-white color temperatures on the Kelvin scale; while following the visual aesthetics of the Planckian locus on the lower/warmer end. There has also been difficulty emulating incandescent lighting colors and dimming performance.
In physics and color science, the Planckian locus or black body curve is the path or locus that the color of an incandescent black body would take in a particular chromaticity space as the blackbody temperature changes. It goes from deep red at low temperatures through orange, yellowish white, white, and finally bluish white at very high temperatures. Black body sources. (i.e., generally any filament bulb or sunlight, but not fluorescent lamps) emit a smooth distribution of wavelengths across the visible spectrum, which means that human eyes and visual system can reliably distinguish colors of non-luminous objects. Subconsciously, humans adapt to differing bias in the illuminant color, and manage to perceive consistent colors in the artifacts handled every day (food, clothes, etc.), despite wide variations in their absolute color. Artificial sources of light, in particular discharge lamps (sodium, mercury, xenon), LEDs, and fluorescent lamps can have extremely spikey spectral distributions, which means their color rendering properties may typically be very poor, even if the overall perceived illuminant color is close to a blackbody color. Color Rendering Index, CRI (sometimes written Ra:Red Average) is often quoted to indicate how accurately that light will portray colors relative to a blackbody source (e.g. the sun) at the same nominal color temperature. By definition, all blackbody sources have a CRI of 100. Fluorescent lamps typically have CRIs in the range 55-85, with 80-85 being classed by the manufacturers as ‘good’ or ‘very good’ color-rendering.
As mentioned above, pixilation is a common drawback of LED lighting where the visible light emitting diodes can catch the viewer's eye due to perceived brightness. LED lighting is usually comprised of an array of light sources that are each a point source of light. Pixilation can be a distraction from the design aesthetic and has been characterized by most as undesirable. Pixilation of LED lighting is usually mitigated by the use of a diffuser lens. A diffuser is usually comprised of a translucent material like acrylic that utilizes white pigment to cover the point sources and blend the perceived pixels (i.e., dots). Diffusers generally will absorb approximately 25% of the light energy in the process. Consequently, by definition, diffusion will widen the given light beam perpendicular to the beam to hide the pixilation and, thus, can be counterproductive when attempting to create a narrow beam.
Further in architectural lighting, there is a need to shape the light beam emitted from a standard 120 degree LED diode to become narrower, to provide farther reach and more “punch.” In many cases light shape can mean the difference between displaying a stripe versus an even light wash on a flat surface. In linear LED lighting, optics and lenses can be integrated into an extruded aluminum housing that doubles as a heat sink for the circuit board electronics. The effect of making a light beam narrower is known as “collimation.” Some existing linear optics are designed to narrow light beams, but have issues with unsightly yellow colored stripes that appear as artifacts at the most narrow beam angles. This effect is known as “color over angle.” Pigment is often added to the diffuser material to mitigate the yellow stripes or to remove unsightly pixilation. These diffuser modifications will increase the diffusing effect and further widen the beam, which is often not desirable.
Thus, it is a long felt need in the lighting field to provide a method of interconnecting a severed tape light segment to an adjacent tape light segment or power source with the ease of the mechanical connector and the benefits of hand soldering. It is also a need to sometimes ensure the light emitted from the LEDS is of a particular or desired character and quality. This disclosure describes an improved connector used to join two severed segments of LED light tape, methods to control the character of emitted lights and ways to diffuse emitted light. One of ordinary skill in the art will appreciate that the aspects can be employed alone, in combination, or in sub-combination(s) to yield the desired lighting effects.